feat(service-spec-importers): registry schema importers accept patches

[mrgrain]

We want to move the service patches from the generic importers package to the specific model package. Generic patches stay with the importers.
To support this, the two registry schema importers now accept an optional patcher.

With that done, we can move the (now unused) service patches to aws-service-spec and use them in the implementation over there.

[github-actions]

@aws-cdk/aws-service-spec: No model change detected

[mrgrain]

@aws-cdk/aws-service-spec: No model change detected

That's what I like to see!

[kaizencc]

this looks like a true refactor. if there's any real changes (beyond adding an option here and there) let me know because i missed it

[mrgrain]

this looks like a true refactor. if there's any real changes (beyond adding an option here and there) let me know because i missed it

I relabeled this as a feat since it's changing the interface for some service-spec-importers. But aside from the additional option, no changes and mostly copying files around.